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Numerical Investigation on the Effects of Design Parameters and Operating Conditions on the Electrochemical Performance of Proton Exchange Membrane Water Electrolysis

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Journal of Thermal Science 2023年第6期32卷 1989-2007页

作者： HASSAN Alamir H. WANG Xueye LIAO Zhirong Xu Chao Key Laboratory of Power Station Energy Transfer Conversion and System of MOE School of EnergyPower and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China Mechanical Power Engineering Department Faculty of Engineering-MattariaHelwan UniversityCairo11718Egypt

Proton exchange membrane electrolysis cell(PEMEC)is one of the most promising methods to produce hydrogen at high purity and low power *** this study,a three-dimensional non-isothermal model is used to simulate the cell performance of a typical PEMEC based on computational fluid dynamics(CFD)with the finite element ***,the model is used to investigate the distributions of current density,species concentration,and temperature at the membrane/catalyst(MEM/CL)***,the effects of operating conditions and design parameters on the polarization curve,specific electrical energy demand,and electrical cell efficiency are *** results show that the maximum distribution of current density,hydrogen concentration,oxygen concentration,and temperature occur beneath the core ribs and increase towards the channel outlet,while the maximum water concentration distribution happens under the channel and decreases towards the channel exit *** increase in gas diffusion layer(GDL)thickness reduces the uneven distribution of the contour at the MEM/CL *** is also found that increasing the operating temperature from 323 K to 363 K reduces the cell voltage and specific energy *** hydrogen ion diffusion degrades with increasing the cathode pressure,which increases the specific energy demand and reduces the electrical cell ***,increasing the thickness of the GDL and membrane rises the specific energy demand and lowers the electrical efficiency,but increasing GDL porosity reduces the specific electrical energy demand and improves the electrical cell efficiency;thus using a thin membrane and GDL is recommended.

关键词： hydrogen production proton exchange membrane water electrolysis gas diffusion layer cell efficiency

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A kinetic study and factor analysis of solar thermochemical membrane reactors for syngas production

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Science China(Technological Sciences) 2025年第1期68卷 203-217页

作者： Jiaxin XING Chao XU Xiangyu SUN Xin XIA Fei JIN Qiongqiong JIANG Jiale GAO Key Laboratory of Power Station Energy Transfer Conversion and System of MOE School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing 102206China Department of Chemistry University College LondonLondon WC1H 0AJUK School of Chemistry and Chemical Engineering Ningxia Key Laboratory of Solar Chemical Conversion TechnologyState Ethnic Affairs CommissionNorth Minzu UniversityYinchuan 750021China

Solar thermochemical conversion technologies are promising for effectively utilizing solar energy by capturing the full spectrum of solar *** overcome the challenges of low energy conversion efficiency and intermittency faced by solar thermochemical conversion,these technologies can be effectively integrated with membrane reactor *** the performance of solar thermochemical membrane reactors has been experimentally tested,the chemical reactions and oxygen transport mechanisms during the energy conversion process remain poorly *** study introduces a resistance network model to elucidate the interactions between interfacial reactions and bulk diffusion during simultaneous oxidationreduction reactions on both sides of the *** analyzed the oxygen flux of the membrane reactor under various operating conditions using this model to identify the reaction/transport-limiting side of the overall *** most effective solar membrane reactor configuration utilizes natural gas and CO_(2),facilitating clean conversion of fossil fuels with significant advantages in fuel production and energy *** CH_4 lowers the overall reaction temperature,maintains low oxygen partial pressure on the sweep side,and produces a synthesis gas with a 2:1 H_2/CO molar ***,a sensitivity analysis was used to explore the relationship between overall fuel production performance and operational parameters,highlighting the critical role of this research in enhancing the reaction and transport performance of membrane reactors and advancing the development of solar-driven thermochemical fuel production technologies.

关键词： thermochemistry oxygen-permeable membrane membrane reactor chemical kinetics

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Strength-ductility synergy in Mg-Gd-Y-Zr alloys via texture engineering in bi-directional forging

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Journal of Magnesium and Alloys 2024年第11期12卷 4709-4721页

作者： Jingli Li Quanfeng Han Xiuzhu Han Xin Yi Institute for Advanced Materials North China Electric Power UniversityBeijing 102206China Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing 100871China Beijing Institute of Spacecraft System Engineering Beijing 100094China

In this work,we successfully fabricate an ultra-high strength Mg-11Gd-3Y-0.5Zr alloy with ultimate tensile strength of 523 MPa and enhanced ductility via cost-effective bi-directional forging (BDF) and subsequent annealing heat *** elucidate the role of BDF and gain a fundamental understanding of the remarkable simultaneous increase of strength and ductility,systematic microstructure characterization and analysis are *** is revealed that the double-peak basal texture,with basal poles located at the center of two mutually perpendicular forging directions,serves as an essential factor for the strength-ductility synergy of the Mg-11Gd-3Y-0.5Zr alloy processed with *** of the double-peak basal texture in overcoming the strength-ductility trade-off include promoting non-basal slip,increasing ductility,and enlarging the Hall-Petch effect along the sample elongation direction while reducing the extent of anisotropy in critical resolved shear stresses of different slip *** study demonstrates that texture engineering is a powerful strategy to control magnesium alloy performance and BDF is a promising processing technique for enhancing mechanical properties of magnesium alloys.

关键词： Bi-directional forging(BDF) Magnesium alloys High strength Texture Anisotropy

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Enhanced AC Fault Ride-through Control for MMC-integrated system Based on Active PCC Voltage Drop

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Journal of Modern power systems and Clean Energy 2023年第4期11卷 1316-1330页

作者： Haihan Ye Wu Chen Heng Wu Wu Cao Guoqing He Guanghui Li Center for Advanced Power Conversion Technology and Equipment School of Electrical EngineeringSoutheast UniversityNanjing 210096China Department of Energy Technology Aalborg University9220 AalborgDenmark China Electric Power Research Institute Beijing 100192China

When a renewable energy station(RES)connects to the rectifier station(RS)of a modular multilevel converterbased high-voltage direct current(MMC-HVDC)system,the voltage at the point of common coupling(PCC)is determined by RS control *** example,RS control may become saturated under fault,and causes the RS to change from an equivalent voltage source to an equivalent current source,making fault analysis more *** addition,the grid code of the fault ride-through(FRT)requires the RES to output current according to its terminal *** changes the fault point voltage and leads to RES voltage regulation and current redistribution,resulting in fault response *** address these issues,this study describes how an MMC-integrated system has five operation modes and three common characteristics under the duration of the *** study also reveals several instances of RS performance degradation such as AC voltage loop saturation,and shows that RS power reversal can be significantly *** enhanced AC FRT control method is proposed to achieve controllable PCC voltage and continuous power transmission by actively reducing the PCC voltage *** robustness of the method is theoretically proven under parameter variation and operation mode ***,the feasibility of the proposed method is verified through MATLAB/Simulink results.

关键词： Modular multilevel converter-based high-voltage direct current(MMC-HVDC)system fault ride-through(FRT) voltage loop saturation continuous power transmission point of common coupling(PCC) active voltage drop control

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CFD Analysis of an 800 kV HVDC Transformer Using Rapeseed Oil as the Cooling Fluid

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CSEE Journal of power and Energy systems 2022年第5期8卷 1508-1518页

作者： Edgardy M.Gutierrez Diaz Gaosheng Wei Liu Cui Key Laboratory of Power Station Energy Transfer Conversion and System(Ministry of Education) School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing 102206China Department of Power Engineering School of Electrical EngineeringBicentenary University of AraguaTurmero 2115Venezuela

This study aims to analyze rapeseed oil’s effectiveness as a coolant of a high-voltage direct current(HVDC)converter transformer while comparing it with mineral *** employed a numerical model,assisted by Computational Fluid Dynamics(CFD)tools,to simulate the convective heat transfer inside a HVDC converter transformer,which is an oil-directed air forced(ODAF)*** model seeks to obtain the temperature and velocity fields at the critical points of the fluid *** simulation domain reproduces a 2D cross-sectional model in the center of the *** results show that rapeseed oil requires more time to gain heat from the core and windings due to its lower thermal ***,the average temperature of rapeseed and mineral oils will not significantly differ once the channel temperature reaches a stable *** indicates that the rapeseed oil can effectively replace mineral oil under the same heating ***,a slower flow of the rapeseed oil allows the fluid to smoothly enter the cooling ***,the rapeseed oil cools these channels by pushing the fluid in them and absorbs heat from the sources earlier than mineral *** improvement in cooling indicates that rapeseed oil is better than mineral oil as a coolant and electrical insulating fluid for power transformers.

关键词： CFD analysis cooling fluid HVDC transformer rapeseed oil

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Strategies toward Highly Efficient Monolithic Perovskite/Organic Tandem Solar Cells

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Chinese Journal of Chemistry 2023年第14期41卷 1753-1768页

作者： Shan Jiang Zhiyang Xu Fuzhi Wang Shilei Tian Yang Wang Chenghao Li Zhan'ao Tan State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing102206 China Beijing Advanced Innovation Center for Soft Matter Science and Engineering Beijing University of Chemical TechnologyBeijing100029 China Department of Coal and Syngas Conversion Sinopec Research Institute of Petroleum ProcessingBeijing100083 China

Constructing monolithic tandem solar cells (TSCs) is an effective method to break the Shockley–Queisser (S–Q) radiative efficiency limit for single-junction solar cells. Employing the wide bandgap perovskite materials and low bandgap organic materials as absorber layers for front and rear subcells, respectively, to construct perovskite/organic TSCs can complementarily absorb sunlight in ultraviolet-visible (UV-Vis) range by front perovskite and near-infrared (NIR) range by rear organic molecules, thus reducing the thermalization energy losses. Besides the subcells, the interconnection layer (ICL), which physically and electrically connects the front and rear subcells, is also an important tunnel junction to recombine charges. In this review, we summarize the optimization strategies of wide bandgap perovskites for front subcell, narrow bandgap organic material for rear subcell, and the ICLs employed in monolithic perovskite/organic TSCs.

关键词： Perovskite solar cells Wide bandgap perovskite Low bandgap organic molecule Tandem solar cells Subcells Interconnection layer Efficiency Open-circuit voltage

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A Novel Adaptive Dead-Time Control Method for GaN-Based Motor Drives

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IEEE Transactions on Energy conversion 2025年第1期40卷 258-269页

作者： Qin, Haihong Zheng, Xiaoxue Wang, Wenlu Xun, Qian Nanjing University of Aeronautics and Astronautics Department of Electrical Engineering Nanjing210016 China Nanjing University of Aeronautics and Astronautics Center for More-Electric-Aircraft Power System Nanjing210016 China RISE Research Institutes of Sweden Unit of Energy Conversion Borås50462 Sweden

Compared to Si devices, Gallium Nitride (GaN) devices are more suitable for achieving high switching frequency in motor drive applications, thereby improving power density. However, increasing switching frequency can also lead to extra switching losses and poor total harmonic distortion (THD). A smaller dead-time can mitigate these issues, but conventional constant dead-time design methods struggle to ensure optimal performance across all load ranges. This paper proposes a novel adaptive dead-time control method for GaN high electron mobility transistors (HEMTs) in phase-legs to simultaneously enhance the efficiency and THD of motor drives. To achieve this, the detailed switching process of GaN HEMTs in a double-pulse test circuit is modeled and analyzed. The optimization principle of the dead-time setting is revealed, considering the tradeoff effect of dead-time on switching losses and THD. The adaptive dead-time control method dynamically adjusts the dead-time under different load conditions. The effectiveness of the proposed method is verified on a 1 kW GaN-based permanent magnet synchronous machine drive platform. Extensive experimental results show that the proposed method can increase efficiency up to 0.85% at full load with a switching frequency of 100 kHz compared to constant dead-time. Meanwhile, THD is reduced by 1.44% under the same condition. © 1986-2012 IEEE.

关键词： Threshold voltage

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Hierarchical polypyrrole@cobalt sulfide-based flexible on-chip microsupercapacitors with ultrahigh energy density for selfcharging system

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Nano Research 2023年第1期16卷 555-563页

作者： Yan Zhao Jihua Zheng Jing Yang Wenjie Liu Fen Qiao Jiabiao Lian Guochun Li Tao Wang Jiangwei Zhang Limin Wu College of Energy Material and Chemistry College of Chemistry and Chemical EngineeringInner Mongolia UniversityHohhot 010021China Institute for Energy Research School of Energy&Power EngineeringJiangsu UniversityZhenjiang 212013China Department of Materials Science Fudan UniversityShanghai 200433China Key Laboratory of Power Station Energy Transfer Conversion and System Ministry of EducationNorth China Electric Power UniversityBeijing 102206China

Herein,we prepare the unique hierarchical polypyrrole@cobalt sulfide(PPy-hs@CoS)hollow sphere-based nanofilms as interdigitated electrodes for flexible on-chip micro-supercapacitors(MSC).Benefiting from the excellent flexibility and high electrical conductivity of PPy-hs combined with the great electrochemical activity of CoS,such PPy-hs@CoS composite material can not only inhibit the volume expansion of PPy but also promote the diffusion of the electrolyte *** PPy-hs@CoS filmbased electrode delivers a greatly improved specific capacitance and small *** functional theory calculations infer that OH−prefers to bind to PPy on CoS@PPy and confirms the synergistic effect of each component for enhanced reaction kinetics.A quasi-solid-state on-chip flexible asymmetric MSC based on PPy-hs@CoS and activated carbon(AC)microelectrodes exhibits large areal-specific capacitance(131.9 mF/cm2 at 0.3 mA/cm2),ultrahigh energy density(0.041 mWh/cm2@0.224 mW/cm2 and 25.6 mWh/cm3@140.6 mW/cm3),and long cycle *** demonstrate the possibility to scale up the PPy-hs@CoS nanofilm microelectrode by arranging two of our asymmetric MSC in series and parallel connections,which respectively increase the output voltage and current.A self-charging system by connecting our asymmetric MSCs with a piece of commercial solar cells is developed as a potential possible mode for future highly durable and high-voltage integrated electronics.

关键词： polypyrrole cobalt sulfide adsorption energy on-chip micro-supercapacitor self-charging device

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Steady-State Operating Area Analysis and Full Unit-Circle Realization for Current Source Converter

Steady-State Operating Area Analysis and Full Unit-Circle Re...

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2024 CPSS and IEEE International Symposium on Energy Storage and conversion, CPSS and ISESC 2024

作者： Song, Zhaoqi Wei, Xiaoguang Zhang, Wenwen An, Ronghui Shan, Yunhai Liu, Jinjun School of Electrical Engineering Xi'An Jiaotong University Xi'an China Advanced High Power Energy Conversion Institute Beijing Huairou Laboratory Beijing China State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University Beijing China

ISBN: (纸本)9798350380514

Current source converter (CSC) with dc fault ride-through capability and low-cost advantages, is attracting lots of attention in high-voltage direct current (HVDC) and renewable energy conversion fields. The steady-state operating area (SSOA) of voltage source converter (VSC) should be designed to achieve the full unit-circle in some utility applications. It's based on proper design of main parameters. But in existing studies on CSC, its main parameters are designed mostly based on unit power factor operation, without considering the full unit-circle realization of SSOA. To fill this gap, first the ranges of key parameters are summarized and then used to derive analytical expressions of SSOA constraints in per unit system for CSC. Second, the conditions for main parameters to realize the full unit-circle SSOA are investigated, revealing the L-C filter parameters' effects on the feasible domain of the rated ac voltage. Finally, while the full unit-circle conditions are satisfied, the minimum capacitor voltage is chosen as the optimization objective in the parameters design. Then the optimized parameters in typical HVDC applications are acquired. It's found that the rated ac voltage designed is relatively high for practical applications, indicating further tradeoffs between full unit-circle SSOA and system cost. © 2024 IEEE.

关键词： Voltage-source converters

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Time-domain and Frequency-domain Analyses of PETT Oscillation in Press Pack IGBTs

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CSEE Journal of power and Energy systems 2023年第2期9卷 682-695页

作者： Jiayu Fan Xiang Cui Xinling Tang Cheng Peng Zhibin Zhao Xiangrui Meng Xuebao Li Zhong Chen State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electrical Power UniversityBeijing 102206China Power Semiconductor Devices Research Institute State Key Laboratory of Advanced Power Transmission TechnologyGlobal Energy Interconnection Research Institute Co.Ltd.Beijing 102209China Department of Electrical Engineering University of ArkansasFayettevilleAR 72701USA

Plasma extraction transit time(PETT)oscillation might appear in IGBT devices,which is harmful to the electromagnetic compatibility(EMC)of a renewable energy *** eliminate this oscillation,its frequency-domain characteristics in wire-bonded IGBT devices have been extensively ***,the time-domain analysis of PETT oscillation,especially in Press Pack IGBT(PPI)devices,has not attracted enough attention *** this paper,PETT oscillations with multi-chips in PPI devices are systematically investigated by *** is first reported there are multiple resonant oscillations at the tail period when multi-chips turn *** overlap in the time domain waveforms,which lead PETT oscillation to be more serious in ***,PETT oscillation is divided into three different feedback states for the first *** the IGBT chip in the PETT oscillation,its physical based model and behavior model are proposed,which further form the equivalent circuit as the two-port ***,it is indicated that only parallel resonances can lead to PETT oscillation,which is consistent with experiment results.

关键词： PETT oscillation press pack IGBTs timedomain analysis two-port network

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